Reciprocable devices typically include a reciprocable member which reciprocates to perform a useful function, such as pumping a flowable material, compressing a gas, metering a fluid or providing a reciprocating output for other purposes. A driving fluid under pressure, which may be either a liquid or a gas, is commonly used to reciprocate the reciprocable member. For example, the reciprocable member may be a piston having first and second faces which are alternately exposable to driving fluid under pressure and to exhaust.
A valve system is provided for controlling the exposure of the piston faces to the pressurized driving fluid and to exhaust. In order for the valve system to perform its function, the valve system typically includes one or more valve elements which must be moved periodically from one position to another to bring about reciprocation of the piston. Movement of the reciprocable member can be used to control movement of the valve elements.
Our prior application Ser. No. 443,589 filed on Nov. 22, 1982, entitled Valve System For A Reciprocating Device discloses a particularly advantageous system for utilizing the reciprocable member to control the valves. This is accomplished with minimum inertia and frictional losses. According to our prior application, bistable spring means, which includes pivotable levers, is drivingly coupled adjacent their respective end portions to first and second valve elements to drive these valve elements. Because the levers pivot, there is an angular relationship between the valve elements and the levers, and this can produce a tendency of the valve elements to cock or become inclined with respect to the desired direction of travel. Although this can be taken care of by utilizing appropriate spherical valve seats, it is desired to provide a more efficient manner of drivingly coupling the bistable spring means to the valve elements.